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Venus
Venus is the second planet from Sol. It has no natural satellite. Venus is a terrestrial planet and is sometimes called Terra's "sister planet" because of their similar size, mass, proximity to the Sun and bulk composition. It is radically different from Terra in other respects. It has the densest atmosphere of the four terrestrial planets, consisting of more than 96% carbon dioxide. The atmospheric pressure at the planet's surface is 90 times that of Terra. With a mean surface temperature of 735 K (462 °C; 863 °F), Venus is by far the hottest planet in the Solar System, even though Mercury is closer to the Sun. Venus is shrouded by an opaque layer of highly reflective clouds of sulfuric acid, preventing its surface from being seen from space in visible light. It may have had oceans in the past, but these would have vaporised as the temperature rose due to a . The water has most probably evaporated, and, because of the lack of a planetary magnetic field, the free hydrogen has been swept into interplanetary space by the solar wind. Venus's surface is a dry desertscape interspersed with slab-like rocks and periodically resurfaced by volcanism. Composition The similarity in size and density between Venus and Terra means they share a similar internal structure: a core, mantle, and crust. Like that of Terra, the Venusian core is partially liquid because the two planets have been cooling at about the same rate. The slightly smaller size of Venus means pressures are 24% lower in its deep interior than Terra's. Surface About 80% of the Venusian surface is covered by smooth, volcanic plains, consisting of 70% plains with wrinkle ridges and 10% smooth or lobate plains. Two highland "continents" make up the rest of its surface area, one lying in the planet's northern hemisphere and the other just south of the equator. The planet has few impact craters, demonstrating the surface is relatively young, at most, 600 million years old. In addition to the impact craters, mountains, and valleys commonly found on rocky planets, Venus has some unique surface features. Among these are flat-topped volcanic features, which look somewhat like pancakes and range in size from 20 to 50 km across, and from 100 to 1,000 m high; radial, star-like fracture systems; features with both radial and concentric fractures resembling spider webs; and circular rings of fractures sometimes surrounded by a depression. These features are volcanic in origin. Much of the Venusian surface appears to have been shaped by volcanic activity. Venus has several times as many volcanoes as Terra, and it has 167 large volcanoes that are over 100 km across. Venusian craters range from 3 km to 280 km in diameter. No craters are smaller than 3 km, because of the effects of the dense atmosphere on incoming objects. Objects with less than a certain kinetic energy are slowed down so much by the atmosphere that they do not create an impact crater. Incoming projectiles less than 50 metres in diameter will fragment and burn up in the atmosphere before reaching the ground. Conditions Venus's surface hotter than Mercury's, which has a minimum surface temperature of 55 K (−220 °C) and maximum surface temperature of 695 K (420 °C), even though Venus is nearly twice Mercury's distance from the Sun and thus receives only 25% of Mercury's solar irradiance. This temperature is higher than that used for . The surface of Venus is often said to resemble accounts of . Dynamics Atmosphere Venus has an extremely dense atmosphere composed of 96.5% carbon dioxide, 3.5% nitrogen, and traces of other gases, most notably sulfur dioxide. The mass of its atmosphere is 93 times that of Terra's, whereas the pressure at its surface is about 90 times that at Terra's—a pressure equivalent to that at a depth of nearly 1 kilometre under Terra's oceans. The density at the surface is 65 kg/m3, 6.5% that of water or 50 times as dense as Terra's atmosphere at 20 °C at sea level. The CO2-rich atmosphere generates the strongest greenhouse effect in the Sol system, creating surface temperatures of at least 735 K (462 °C) Climate Billions of years ago Venus's atmosphere was much more like Terra's than it is now, and that there may have been substantial quantities of liquid water on the surface, but after a period of 600 million to several billion years, a runaway greenhouse effect was caused by the evaporation of that original water, which generated a critical level of greenhouse gases in its atmosphere. Winds at the surface are slow, moving at a few kilometres per hour, but because of the high density of the atmosphere at the surface, they exert a significant amount of force against obstructions, and transport dust and small stones across the surface. This alone would make it difficult for a human to walk through, even if the heat, pressure, and lack of oxygen were not a problem. Winds on Venus move at up to 60 times the speed of its rotation, whereas Terra's fastest winds are only 10–20% rotation speed. The surface of Venus is effectively isothermal; it retains a constant temperature not only between day and night but between the equator and the poles. Although having a 177 degree tilt, starting from 180 degrees, Venus has a 2.64 degree tilt, leaving little variation by seasons. Orbit and rotation Venus orbits the Sun at an average distance of about 0.72 AU (108,000,000 km; 67,000,000 mi), and completes an orbit every 224.7 days. Although all planetary orbits are elliptical, Venus's orbit is the closest to circular, with an eccentricity of less than 0.01. All the planets in the Solar System orbit the Sol in an anti-clockwise direction as viewed from above Terra'snorth pole. Most planets also rotate on their axes in an anti-clockwise direction, but Venus rotates clockwise in retrograde rotation once every 243 Terrandays—the slowest rotation of any planet. Because its rotation is so slow, Venus is very close to spherical. A Venusian sidereal day thus lasts longer than a Venusian year (243 versus 224.7 Terran days). Venus's equator rotates at 6.5 km/h (4.0 mph), whereas Teranis approximately 1,670 km/h (1,040 mph). One Venusian year is about 1.92 Venusian solar days. To an observer on the surface of Venus, Sol would rise in the west and set in the east.An explanation for the lack of satellites is the effect of strong solar tides, which can destabilise large satellites orbiting the inner terrestrial planets. Civilization Initial Settlement and colonies Terraformation The now terraformed Venus is the second most populated object or planet in the Sol system, with over eight billion humans living on the surface. To reverse the runaway greenhouse effect, the Conglomerate had to overcome several issues. *Reducing Venus's surface temperature of 462 °C (864 °F). *Eliminating most of the planet's dense 9.2 MPa (91 atm) carbon dioxide and sulfur dioxide atmosphere, via removal or conversion to some other form. *Addition of breathable oxygen to the atmosphere. Venus receives about twice the sunlight that Earth does, which is thought to have contributed to its runaway greenhouse effect. Terraforming Venus involved reducing the insolation at Venus's surface to prevent the planet from heating up again. Sunlight and radiation exposure Solar shades were first placed in orbit to reduce the total insolation received by Venus, cooling the planet significantly. The first shade, placed in the Sol–Venus L1 Lagrangian point also blocks the solar wind, removing the radiation exposure problem on Venus. The shade itself is four times the diameter of Venus itself at the L1 point, required to be constructed in space. There was a massive problem, as radiation pressure turned the solar shade into the largest solar sail ever. The Conglomerate solved this by using polar-orbiting, solar-synchronous mirrors that reflect light toward the back of the sunshade, from the non-sunward side of Venus. Photon pressure pushes the support mirrors to an angle of 30 degrees away from the sunward side. Solar shades also serve as solar power generators, beamed back to Venus. After terraforming, there were still several problems, such as Venus's day being longer than it's year. This was solved with an artificial rotating soletta mirror in a polar orbit, which produces a 24-hour light cycle, made out of recycled material from solar shades used in the prime stages of terraforming. Cooling Cooling of Venus was relatively simple once the solar shades were deployed. The temperature of carbon dioxide in the atmosphere gradually fell to critical point of itself, at 304 K (30.85 C°, 87.53 F°). Following this, it began to rain liquid carbon dioxide until the surface pressure of Venus was lowered to 74 bars (73 terran atmospheres), a point where the temperature began to fall again. Along with this, the carbon dioxide rain continues to fall as it settle in the lowlands of Venus and forms oceans. At 217 K (-56 C°, -69 F°) and 5 bars (4.9 terran atmospheres), the seas and oceans begin to freeze over and the carbon dioxide rain turns into snow. By this point, carbon dioxide is being shipped off-planet in the tons to other terraforming missions and for sale, able to supply carbon dioxide demands for decades. This off-world shipping required hundreds of thousands of transport ships to transport the carbon dioxide to space stations in low venusian orbit, still being sold today. Even then, the shipping itself required a few years of around the clock man hours. With continuous cooling, temperature drops to 192 K (-81 C°, -114 F°) and there is only 0.8 bar (0.78 terran atmospheres) of carbon dioxide left in the atmosphere, and 2 bars (1.9 terran atmospheres) of nitrogen. The remaining dry ice that didn't get off the surface was then covered. Following this, cooling was reversed and the planet was warmed to 290 K (17 C°, 62 F°) This entire process took about thirty years, which was sped up compared to the original designs proposed by Kojima Tanosuke. This was achieved by adding heat pipes constructed out of carbon nanotubes. These large tubes blasted heat to the radiating edge of the atmosphere, especially during the early phases. The new dry ice on the surface soon sank into the Venusian crust and pushed the continent upwards, producing planet-wide quakes, rivalling that of an asteroid impact. Along with sinking into the crust, substantial amount of carbon dioxide also sank into the Venusian soil. With the majority of the atmosphere dealt with, the remaining atmosphere was converted and tweaked to terran atmosphere proportions; about 78% nitrogen, 20.9% oxygen, and 0.93% argon. The high amount of oxygen was achieved by photosyntetic microorganisms being placed into the Venusian atmosphere, producing the needed oxygen within five years. The planet gradually warmed again and the resulting temperature is 297.15 K (24 C°, 75.2 F), 9 C° higher than Terra. Water Still parched and dry, additional off-world water was needed for Venus to sustain terran conditions. Three of Pluto's satellites were chosen to deliver water to Venus, producing an ocean with a 100 meter (344 feet) depth. The moons had to be ejected from the Plutonian system with gravity assists from Proserpina. Heading on a trajectory with Jupiter, the gas giant then redirected the moons into the inner Sol system. The 3 former moons of Pluto swung by Venus right before the atmosphere cooled, wasting no time in the process, and decreasing in velocity every encounter. It encountered Venus evey 112 days, eventually disintegrating into the Venusian atmosphere. Huge holes were required to be drilled into the dry ice surface to let the water escape. Foamed rock was then layered over this, filled with carbon dioxide gas to keep the remaining dry ice from evaporating. Eventually, the dry ice began to turn into gas, but by then, export far exceeded leakage. The new 100m (344 feet) water ocean covers about 80% of the planet, compared to Terra's 70%, allowing for a land surface area of 91.8 million kilometers (57 million miles), compared to Terra's 149 million kilometers (92.6 million miles). The average ocean temperature on Venus is about 26 C°, making the vast majority of the planet's waters tropical. Magnetic field Even with the presence of an ozone layer and a real atmosphere, these by itself could not stop the entire population from getting skin cancer. The lack of magnetosphere around Venus was solved by the first implementation of an artificial magnetic field. Instead of dropping nuclear or antimatter bombs in the billions of gigatons range down into the core to restart the internal, the Conglomerate simply ran 12 superconducting rings underground aligned with latitude. It requires about a gigawatt of power constantly to continue operation, while carrying a 6.4 MA current, protecting the planet from cosmic and solar radiation, this is powered by a relatively small fusion reactor with backup solar panels. Geography and human geography The economy of Venus itself is self-sufficient, thanks to terraforming efforts in the 21st century, and follows a standard terran economy model. The planet focuses on advanced consumer products and scientific research. Venus has a population of 8.72 billion, six billion less than Terra. Due to Venus's proximity to Sol, inhabitation for humans with pale skin is near impossible. Most of the people on Venus have caramel skin at the least. The planet is a treasure agriculturally. Being nine degrees hotter than Terra in Celsius, Venus is a tropical paradise, with the vast majority of plants and animals on the planet being of tropical terran descent. Solar power is much more prominent on Venus than Terra or Mars, due to receiving four times more sunlight. Other than these differences, Venus is similiar to Terra in all other ways, specifically in economy. Category:Planets Category:Sol system Category:Terra-like